In the past decade and still today, the research and development effort for new products in the manufacturing industry of conventional laminated hardwood floor are mainly focused on the development of a floor using composite material which will increase the durability, the strength and the moisture protection of the cargo-carrying trailer/container floor. The weight of the new composite floor should, at minimum, have the same weight or preferably have less weight. Furthermore, all of the objectives should be reached at the lowest manufacturing cost.
Solutions to resolve these problems have been proposed by many in this field, and more recently by Padmanabhan U.S. Pat. No. 5,928,735 and Tunis U.S. Pat. No. 6,601,357.
Padmanabhan applies a reinforced thermoplastic ply to the entire bottom of the floor. Because reinforced ply increases the strength and stiffness of the trailer floor, the hardwood portion of the floor can be thinner. The result is a stronger and lighter trailer floor. The reinforced ply provides also a water impervious layer protecting the entire bottom part of the floor from moisture coming from the road.
Tunis provides a solution for moisture protection only. The thermoplastic ply is not reinforced and has as its sole purpose the protection of the floor from the attack of water spray and moisture over time. The thermoplastic ply covers the entire bottom surface of the floor.
The above-mentioned patents implicitly appear to be based on the same assumption: the entire area of the laminated hardwood cargo-carrying floors is exposed equally over the time to the same accumulation of the effects of stress and/or moisture attack. Based on that assumption, all the proposed solutions taught in the above-mentioned patents require necessarily that the remedy needs to be applied to the entire surface of the bottom part of the laminated hardwood floor. Furthermore, the reinforced and/or impervious moisture ply has the same thickness or the same degree of reinforcement or moisture protection all over the bottom floor.
In reality, different sections of the laminated hardwood cargo-carrying floor are not subject to the same accumulation effect of stress or exposition of moisture over time.